Understanding Rotation in Blender (scales on sphere)
If you wanted to rotate an object around its z local axis in blender, what do you do? Do you change the rotation z euler value? Or do you use the rotate operator in the local transform orientation? Changing the rotation euler's values rotates the object in its global space, not in its local.

So, how do we rotate in local space in Animation Nodes? The answer is matrix multiplication which is the underlying mathematics behind blender's rotation operators. Compose a translation matrix that include the object's locations, then multiply that by the Rotation Matrix Output of the Direction To Rotation Node, then multiply the result by a rotation matrix, the last matrix act as the local transformation, so by editing its values, you are locally transforming.



Another method would be to use Hamilton product on Quaternions, they are a little harder to understand though. Simply multiply your quaternions by another that include your local rotation information.



Yet another method would be to edit the guide axis to account for your rotation. See the documentation.